Crystal whiskers of chromium, nickel, iron, copper and gold, with diameters of less than 10 −3 mm and lengths up to 0.3 mm, were grown by deposition from the vapor phase. The growth behavior for these metals was consistent with the mechanism proposed by Sears, to account for the growth of mercury, cadmium, zinc and silver whiskers by vapor deposition. However, the growth of whiskers was prevented when the partial pressure of oxygen in the growth zone was greater than the dissociation pressure of the metal oxide. This accounts for the lower limit of metal-vapor pressures encountered in the growth experiments with oxide forming metals and is substantiated by the non-existence of this limit in experiments carried out with gold. The technique used in this investigation provides a means of obtaining the required low-oxygen partial pressures, establishing small temperature differences primarily by radiation, and permits a direct measurement of the evaporation and growth substrate temperatures during an experiment. Several experiments were carried out on the α-γ transition of the vapor grown iron whiskers. It was found that they did not deform by kinking, except in special cases, as has been observed for halide-grown iron whiskers when they were heated or cooled through the transition temperature of pure iron. The only explanation that will satisfy all of the observations is that α-iron, in the form of small whiskers, can be super-heated several hundred degrees for several hours.